Does the crown-implant ratio affect the survival and complications of implant-supported prostheses? A systematic review

Statement of problem. The use of dental implants shorter than 10 mm in length increases the crown-implant ratio. Whether an increased crown-implant ratio affects the survival rate and complications is unclear. Purpose. The purpose of this systematic review was to investigate the effect of the crown-implant ratio on the survival rate and complications of implant-supported prostheses Materials and methods. Five databases (PubMed, MEDLINE, Scopus, Google Scholar, and Cochrane) were electronically and manually searched for longitudinal studies with a follow-up period of 3 years or longer. The study question was "Does the crown-implant ratio affect survival rate and complications of implant-supported prostheses?" The outcomes investigated were implant survival rate, peri-implant bone resorption rate, implant fracture rate, and other technical complications in the implant components. Results. A total of 670 studies were identified from the research in the databases. By applying the inclusion and exclusion criteria to the full texts, 17 articles were included for descriptive analysis. Qualitative data analysis showed that the survival rate of implant-supported prostheses with a crown-implant ratio greater than 2 was 97.2%, and for a ratio lower than 1, it was about 97.6%. Moreover, 9 papers reported that increasing the crown-implant ratio reduced bone resorption, while 8 other studies reported no significant association between the increase in the crownimplant ratio and bone resorption. Conclusions. No significant relationship was found between the crown-implant ratio and implant survival rate. However, increasing the crown-implant ratio is likely to decrease bone loss around the implant. Information was insufficient to analyze the relationship between the crown-implant ratio and technical complications in implant-supported prostheses. (J Prosthet Dent 2024;131:819-25)